Normal air diffusion reduces tire pressure over time so that the natural state of tires is underinflated. Accordingly, drivers should constantly check tire pressure to avoid increased fuel consumption or wear and to avoid impeded braking and/or handling performance. Even more, a substantially underinflated tire may constitute a severe safety risk. Tire pressure monitoring systems have been proposed to warn drivers when tire pressure is significantly low. Such systems, however, remain dependent upon the driver taking remedial action when warned to reinflate a tire to a recommended pressure.
It is preferable, therefore, to provide components which allow or help to provide an automatic inflation of a tire without requiring any action of the driver.
U.S. Patent Application 2012/0160386 A1 discloses a pump and actuator assembly for a self-inflating tire. The described tire system includes a compression actuator assembly mounted to a tire carcass for compressing air for delivery to a tire cavity. The compression actuator assembly includes a hollow cylindrical containment body formed from a resilient deformable material composition and containing a quantity of non-compressible fluid medium. The containment body is affixed to a relatively high flex-deformation region of the tire carcass and reciprocally transforms between a deformed state and a non-deformed state responsive to the deformation and recovery of the tire high flex deformation region in a rolling tire. Accordingly, the containment body in the deformed state displaces a pressurized quantity of the non-compressible medium which generates a compression force for application to a volume of air delivered to the tire cavity. A pump assembly is affixed to the tire carcass and includes valves for reciprocally opening and closing the inlet opening and the outlet opening of a compressor body synchronously with the cyclic transformation of the containment body.
US 2012/0241064 A1 discloses an air-maintenance tire system having a compression actuator mounted to the tire carcass and configured for operative actuation by tire deformation during a tire revolution. The system further comprises a pump assembly affixed to the tire carcass and including a compressor body affixed to the compression actuator and having an internal air chamber, wherein the air chamber has an inlet opening for admitting air into the internal air chamber and an outlet opening for conducting air from the internal air chamber to the tire cavity. The air compressor body further includes a deformable membrane valve member and an outlet valve member located within and at opposite respective ends of the internal air chamber. Furthermore, the compression actuator includes a hollow containment body formed from a resilient deformable material composition and containing a quantity of a non-compressible medium. The containment body is affixed to a relatively high flex-deformation region of the tire carcass and reciprocally transforms between a deformed state and a non-deformed state to generate a deformation force against a membrane valve member surface and deform the membrane valve between the open and closed positions within the air chamber.